1. Field of the Invention
The present invention relates to a honeycomb structural body and a method for manufacturing the same.
2. Description of the Related Art
Hitherto, as a joined body, a joined body in which a pair of electrodes each formed of a metal layer is provided on a surface of a honeycomb body formed of a porous ceramic has been proposed (for example, see Patent Literature 1). According to this joined body, the metal layer contains Cr and/or Fe, a diffusion layer formed of a metal silicide is present at a boundary portion with the honeycomb body, and the reliability of the electrical connection is ensured in a high-temperature environment. In addition, as the joined body, a joined body has been proposed in which pores of a porous ceramic are filled with a ceramic, and a metal component is joined to the porous ceramic with an active metal-containing solder material interposed therebetween (for example, see Patent Literature 2). In this joined body, the porous ceramic and the metal component are joined to each other using a Ag—Cu eutectic crystal. Furthermore, as the joined body, a joined body in which a ceramic member formed of a silicon nitride sintered body and a metal member are joined to each other with a buffer layer interposed therebetween has been proposed (for example, see Patent Literature 3). In this joined body, the buffer layer is configured so that a silicon nitride sintered body layer containing 5 to 20 percent by mass of a nitride of an active metal, a low-Young's modulus metal layer formed of a transition metal and an alloy thereof, and a silicon nitride sintered body layer containing 25 to 70 percent by mass of a nitride of an active metal are sequentially arranged.
As a honeycomb structural body, an exhaust gas cleaning apparatus has been proposed in which the thickness of a partition wall of a cylindrical carrier is set so that electrical resistances of all current paths between terminals are equal to each other, and the cylindrical carrier is heated by supplying electricity thereto through electrodes to increase the temperature of a catalyst supported by the carrier to its active temperature (for example, see Patent Literature 4). It has been disclosed that according to this structural body, the carrier is uniformly heated, and even at cold start of an engine, the catalyst supported by the carrier can be heated to the active temperature. In addition, as the honeycomb structural body, a honeycomb structural body has been proposed in which from a composite material containing MoSi2 and at least one type of Si and SiC, electrode films, electrode terminals, and a substrate are manufactured (for example, see Patent Literature 5). It has been disclosed that this structural body can be configured to have a low volume resistivity and a low temperature dependence thereof as compared to those of SiC, SiC—Si, or the like. Furthermore, as the honeycomb structural body, a honeycomb structural body has been proposed in which a pair of electrode portions is formed so that each electrode portion has a belt shape extending in a cell formation direction (for example, see Patent Literature 6). It has been proposed that in this structural body, the electrode is formed using SiC or Si.